Apparatus for building and weighing stacks of sheets



K. G. L. LlNDQVlST A ril 10,1962

APPARATUS FOR BUILDING AND WEIGHING STACKS 0F SHEETS Filed Dec. 15,1958v 2 Sheets-Sheet 1 INVENTOR. K N! G'o'gt; lemur-tL/nd CUM- 8min.)

April 10, 1962 K. G. L. LINDQVIST APPARATUS FOR BUILDING AND WEIGHINGSTACKS OF SHEETS 2 Sheets-Sheet 2 Filed Dec.

INVENTOR.

Ka $55152 Lemur-t Luhdfmf 3,028,980 Patented Apr. 10, 1962 United StatesPatent )fifice APPARATUS FOR BUTLDHNG AND WEIGHYNG STACKS F SI-EETS KarlGtista Lennart Lindqvist, Nasbyparlr, Sweden, as-

signor to Svenslra AB Toledo, Stockholm, dwcden, a corporation of SwedenFiled Dec. 15, 1958, Ser. No. 780,558 3 Claims. (Cl. 214-4) Thisinvention relates to apparatus for building stacks, having uniformWeight and dimensions, of sheets of variable weight delivered inadjacent rows. More specifically the invention relates to layboys orapparatus adapted to receive sheets of wood pulp, cut from a continuousweb as produced in a pulp mill, and to arrange the sheets in stacks ofpredetermined weight and uniform height for baling.

The amount of water in a web of pulp issuing from a pulp machine isgenerally greater in the marginal portions of the web. This causes thesheets from the outside rows of the sliced web to be heavier due totheir greater water content than the sheets from the inner rows, whilenot being any thicker. Bales formed from the outside sheets do notrequire as many sheets to reach the desired weight and will be shorterthan the bales built from the inner rows of sheets.

This has several undesirable effects. One is that the lack of uniformityin size makes packing for shipping or storage more difiicult. Anotherserious consequence is that the water content of a bale built from thesheets of an outside row is greater than that built from an inside row,while the proportion of pulp is lower. As pulp content is the basicprice factor this variation makes evaluation most difiicult. Also itcomplicates accurate processing of such pulp in some subsequent chemicaloperations where the water component must be uniform.

For these reasons methods have been developed for building stacks to therequired weight with approximately an equal number of sheets from eachrow of sheets as created by slicing and cutting the web of pulpdischarged by the pulp forming equipment. These methods have not been asaccurate in results as desired because they utilized quite a number ofconsecutive sheets from each row and uniformity of the bales was thusmore likely to be affected by any change in moisture contentlongitudinally of the web. Also such methods have met with difficultiesin handling the sheets at the higher production rates required by recentmarket demands.

The principal object of this invention is to provide layboy apparatusfor rapidly forming stacks of sheets of pulp as close as possible to theexact weight desired in the final bale.

A further object of the invention is the provision of means forautomatically proportioning, stacking and weighing sheets of pulp ascontinuously delivered from a high production pulp machine.

The apparatus of the invention by which these objects are attainedutilizes a belt conveyor arrangement moving crosswise of the outlet endof the pulp machine to receive the several rows of sheets delivered bythe machine and to continuously carry the sheets to a stacking andweighing station at one end of the apparatus disclosed herein is adaptedto a pulp machine from which four rows of sheets are discharged.

The speed of the belt conveyor is sufiiciently faster than the feedingmovement of the pulp web to carry one sheet of each row deposited on theconveyor to the stacking and weighing station before the next cross setof one sheet from each row drops upon the conveyor. The ap paratusincludes means for holding the sheets during this fast travel toward thestacking station.

The layboy apparatus provided by this invention will be describedhereafter with reference to the embodiment shown in the accompanyingdrawings, in which:

FIGURE 1 is a side elevation of an apparatus embodying one form of theinvention;

FIGURE 2 is a frontal view of the apparatus of FIG- URE l with portionsremoved; and

FIGURE 3 is a plan view of a device constituting a part of the apparatuswhich temporarily receives sheets at the weighing station of theapparatus, while a stack of the desired weight is transferred from thestation.

The conventional pulp trimming machine, which cuts the continuous pulpstrip into sections or sheets, is not shown in the accompanyingdrawings, as it is not thought essential to a clear understanding of theoperation of the present layboy apparatus which, it is to be understood,is applicable to various types of pulp trimmers, slitters and cutterswithout any material change.

It will also be stated that while the present apparatus is applicable tothe stacking of sheets of pulp, cardboard, paper and the like, in thefollowing description it will be described in connection with thestacking of sheets of pulp, but with the understanding that thedescription relates equally to the other uses.

The pulp, as it comes to the trimming machine, is in the form of acontinuous web, usually eight, ten or more feet in width. In thetrimming machinev the web is trimmed along the edges, slit lengthwiseinto aplurality of strips of predetermined width, and is thencutltransversely to produce the rectangular pieces or sheets of standardsize.

The present continuous layboy provides means for receiving these cutpieces or sheets from the trimming machine, and for delivering themsuccessively upon a crosswise traveling staclring conveyor.

For purposes of discussion the web of pulp will be considered as havingan original width of twelve feet and to be sliced into three foot stripswhich are cut into two foot sections. The web is thus divided intosheets three feet across by two feet wide lengthwise of the web.

Referring to the drawings in more detail, the layboy apparatus thereillustrated includes a feeding device mounted upon side plates 14). Apair of upper rollers 12 and a pair of lower rollers 14 are rotatablysupported across the ends of plates 10 with their end shafts 16journalled in bores in the plates.

Twelve narrow, fabric belts 18 run between the upper rollers 12.. Theseendless belts are disposed in four groups of three belts each. There arealso sixteen of the belts 18 running between the lower rollers 14'.

The belts on the lower rollers are arranged in four groups of four beltseach. The four belts of each of these last mentioned groups are spacedand located to receive between them the three belts of a group runningbetween the upper rollers 12. Each set of belts, including three upperand four lower belts, is designed to receive and propel one of the fourrows of sheets arriving from the pulp machine.

Through sprockets and a chain drive the belts 18 are driven continuouslyat a precise speed by an electric motor and an associated speed reducer.For purposes of this invention the rate of movement of belts 18 may bedefinitely higher than that of the slicing machine from which the sheetsof pulp are received by the belts. This establishes spacinglongitudinally of the belts between each lateral set of four sheets,although overall delivery rate of the sheets is not increased.

If for instance, the slicing machine carries the pulp at twenty feet perminute, the belts may be driven at sixty feet per minute which wouldleave four feet free longitudinally of the belts between each lateralset of sheets, the sheets being two feet wide lengthwise of the beltsand three feet long in their transverse dimension. This interveningspace of four feet at the cited rate of travel of the belts provides aperiod of four seconds between the release by the belts of one lateralset of sheets and the ginning of the discharge from the belts of thenext lateral set.

Positioned crosswise of the outlet ends of belts 13 is belt conveyor 20upon which the sheets, issuing from belts 18 in four longitudinal rows,are deposited. Conveyor 20 travels around drums 22, the end shafts 24 ofwhich are lodged in bores in opposite sides of the easing 26.

By connection with an end shaft 24 of one of the drums 22 a motor unit19 drives the belt at a speed which may be in this case one hundred andeighty five feet per minute.

Above conveyor 20, on the side away from delivery belts 18, is a sheetretaining belt 28. it is turned around a pair of rollers 30 for movementalong substantially the full length of conveyor 20. End rollers 30 andintermediate idler rollers 31, for supporting the belt 23, are mountedthrough their shafts 32 between the sides of U-beam 34. This beam 34 issupported upon three arms 36 which are pivotally connected to brackets38 on the casing 26.

Belt 28 is brought downward against conveyor 20 and pulled upwardtherefrom by swinging movement of the beam 34 on brackets 38. Thismovement is motivated by the fluid driven plunger 49 from cylinder 42,the plunger being connected to the beam 34. Cylinder 42 is suspendedfrom the angled post 44 extending upwardly from the casing 26. Belt 28is driven by motor 46 at a rate synchronized with that of conveyor 20.Motor 46 is carried on beam 34 and has a belt driving connection withroller 30. The interval between the delivery to conveyor 20 ofsuccessive lateral sets of sheets from belts 18 leaves open space forthe upward swing of belt 28 on beam 34.

At the discharge end of conveyor 20, shown at the left in FIGURE 2, is aweighing and stacking table 48 sitting upon the platform of a weighingscale 50 which in turn is supported upon legs 52. The dial 54 of thescale has a conventional swinging indicator needle.

Within table 48 are mounted normally stationary wheels 56 the rims ofwhich extend above the top of table 48 to provide supporting elementsfor a stack 58 formed of sheets arriving from conveyor 20. Slots 66extend downwardly in table 43 between the rows of wheels 56.

Projecting horizontally into the slots 60 are a series of parallelfingers 62. These are carried on a bar 66, as shown in FIGURE 3, whichis fixed to the end of a piston rod 68. The latter is retractable withfluid actuated movement of the piston within cylinder 76. A guide block72 supports cylinder 70 and in turn is vertically slidable within theupright channel 74. This vertical movement of block 72 is controlledwith electrically operated mechanism or by a fluid driven piston.

In line with the stacking table 48 and the conveyor 20 is an additionalconveyor '76 with rotating elements 78 for transporting a stack 58 ofthe desired weight to a baling station after it has been removed fromthe stacking table 48.

In the operation of this apparatus under the conditions prescribed fordiscussion purposes, it is associated with a pulp machine producing aweb having a twelve foot width and progressing through the trimming andcutting mechanism at the rate of twenty feet per minute. It isconsidered that this mechanism slices the web into four strips of threefoot width which are divided by lateral cuts into two foot sections.Accordingly four rows of sheets with a broad dimension of three feet anda longitudinal stretch of two feet are delivered to the feeding belts18.

As the travel of belts 13 is arranged to be sixty feet per minute orthree times as rapid as the web advancing movement through the trimmingand cutting mechanism,

each transverse set of sheets reaching belts 13 are pulled away from thesubsequent set not yet released by the trimming mechanism. Due to thedifference in speed of the belts and the mechanism a longitudinalspacing of four feet between lateral sets of sheets carried by the beltsis thus established. As previously stated this spacing results in a foursecond interval following the deposit of each lateral set of sheetsbefore the next lateral set starts to leave the belts.

Within this period of four seconds conveyor 20 carries the four sheetsreceived thereon to the stacking station 48 and thereby is ready toreceive the following set. As the four sheets are three feet longlengthwise of conveyor 20 and are separated slightly in the slittingoperation, conveyor 20, in the present instance, must move somewhatfaster than twelve feet in the four second interval or about one hundredand eighty five feet per minute.

At this high speed it is desirable to hold the sheets in place uponconveyor 20. This is accomplished by press ing the retaining belt 23which is traveling at the same rate as conveyor 20 against the depositedsheets. The belt 23 is swung downwardly by precisely timed descent ofplunger 40 through admittance of fluid to cylinder 42. The belt is thusheld down for a period approaching four seconds and is withdrawnupwardly for a period of two seconds for the receipt of the next set ofsheets upon conveyor 20. This timing may be synchronized mechanically bya cam operated fluid valve or through electronic timing elements.

The sheets received by conveyor 20 are thus delivered in single file,with one sheet at a time from each longitudinal row formed from theoriginal pulp web, to the stacking and weighing table 48. The sheetsprojected by conveyor 26 upon the weighing table are vertically alignedthereon by abutment against the plate 80. The latter is raisablysuspended from the pivotal mounting 82.

The sheets continuously accumulate on the stacking and weighing table 43in series of one from each of the four longitudinal rows as cut by thetrimming and slicing mechanism. There is accordingly no concentration ofeither the marginal sheets carrying more water or of the drier centersheets.

When the stack on table 48 reaches the desired final weight a reportingdevice deacts to the arrival of the indicator needle at thepredetermined point on the dial 54. This may be a photoelectric cell ora magnetically sensitive element. In immediate response thereto fingers62 are forced outwardly above the stack, from a neutral position at therequired height, to temporarily receive sheets arriving from conveyor20. The pivotal mounting 82 is also motivated to raise stop plate 89.The wheels 56 simultaneously react to the signal and are motivated tomove the stack over to conveyor 76 for delivery to the subsequent balingstation.

Following placement of the stack on conveyor 76 the fingers 62 are moveddownwardly into the grooves 60 by the fluid driven piston connectionwith the sliding guide member 72. Stop plate 36 is likewise moveddownwardly from its upward position wherein it has acted as a stop forthe sheets received by the fingers 62.

As soon as the sheets accumulated upon the fingers 62 are received ontable 48 by the entry of the fingers in grooves 66 the cylinder 70functions to withdraw piston rod 68 and the fingers from the grooves,and the slide member '72 is raised to bring the fingers back to theirupward neutral position ready for projection into the path of sheetsfrom conveyor 20 as soon as the next stack on table 48 reaches the setweight.

It may be concluded from the preceding that the objects of the inventionhave been fully attained through the disclosed apparatus. Stacks arecreated from sheets taken singly from successive rows of the originalweb of wood pulp in a manner whereby differences in the sheets are bestcompensated for, and a method is provided for handling the stacking ofsheets delivered at a high production rate.

Various modifications in the disclosed embodiment of the invention maybe made without departing from the spirit of the invention. For instancea suction chamber below conveyor belt 20 may be utilized for retainingsheets thereon during their transit to the stacking station 48 in placeof the retention belt 28.

It should be understood that specific dimensions and rates of travelhave been set forth for purposes of explanation only and that such datashould not be taken as that necessarily preferred for practicing theinvention.

Other alterations and substitutions may be made within the precepts ofthe invention and scope of the accompanying claims.

I claim:

1. Apparatus for building stacks, possessing uniform weight anddimensions, of sheets issuing in closely arrayed lateral andlongitudinal rows from a wood pulp machine, said apparatus including asupplemental conveyor first receiving the sheets issuing from the woodpulp machine, driving means operating the supplemental conveyor at asubstantially higher speed than the pulp machine whereby the lateralrows of sheets on the supplemental conveyor are spaced apartlongitudinally thereof, a continuously moving conveyor positionedcrosswise of the discharge end of the supplemental conveyor forreceiving successive lateral rows of sheets, a stacking station at oneend of the continuously moving conveyor upon which the sheets of eachsuccessive row of sheets are deposited, the continuously moving conveyortravelling at a suflicient speed to deliver one row of sheets to thestacking station before the next row of sheets leaves the discharge endof the supplemental conveyor, means holding the sheets on'thecontinuously moving conveyor while they are travelling thereon, saidmeans being operative when sheets are on said conveyor, but arranged tobe out of the path of the sheets as they are received on said conveyorfrom the supplemental conveyor.

2. Apparatus according to claim 1 in which the means holding the sheetscomprises a travelling belt, a pivotable support therefor, and mechanismfor periodically pivoting said support to bring the travelling belt downupon sheets on the continuously moving conveyor.

3. Apparatus according to claim 2 in which the travelling belt isnarrower than the continuously moving conveyor and is brought down upona side portion only of sheets on the continuously moving conveyor.

References Cited in the tile of this patent UNITED STATES PATENTS2,061,782 Stroud Nov. 24, 1936 2,612,981 Alden Oct. 7, 1952 2,795,312Howdle June 11, 1957 2,839,205 Toby et a1. June 17, 1958 2,849,236Beaulieu Aug. 26, 1958 2,877,883 Lanharn Mar. 17, 1959 2,930,493 Sunbladet al. Mar. 29, 1960

